胰高糖素样肽-1(7-36)NH_2引起胰岛β细胞cAMP的变化

Effect of glucagon-like peptide-1(7-36)NH_2 on cAMP content in rat pancreatic β-cells

目的 探讨GLP -1(7-36 )NH2 促胰岛素分泌的细胞内机制。方法 用放免法检测GLP -1(7-36 )NH2 在不同葡萄糖浓度下对培养的新生大鼠胰岛 β细胞的胰岛素分泌量和cAMP含量的变化。 结果 在 2 .8mmol/L葡萄糖时 ,GLP -1(7-36 )NH2 使 β细胞胰岛素分泌和cAMP含量无明显增加 ;优降糖能使胰岛素分泌增加 ,而cAMP含量无明显变化。在 5 .6 ,11.2和 16 .7mmol/L葡萄糖时 ,GLP -1(7-36 )NH2 使胰岛素分泌和cAMP含量均明显增加。在 16 .7mmol/L葡萄糖时 ,加入EGTA或硝苯吡啶后 ,GLP -1(7-36 )NH2 不能引起胰岛素分泌 ,但仍使cAMP含量增加。结论 GLP -1(7-36 )NH2 具有葡萄糖浓度依赖的刺激cAMP生成的作用 。

Objective To explore the cellular mechanisms by which GLP-1(7-36)NH 2 stimulates insulin secretion in β-cells.Methods\ Radio-immunological methods were used to determine the amount of insulin secretion and cAMP content in cultured neonatal rat pancreatic islet cells which were incubated with GLP-1(7-36)NH 2 in different glucose concentration.Results\ In the presence of 2.8 mmol/L glucose,GLP-1(7-36)NH 2 could not increase insulin secretion and cAMP content in β-cells,but glybenclamide increased insulin secretion without changing cAMP content.In the presence of 5.6,11.2 and 16.7 mmol/L glucose,GLP-1(7-36)NH 2 produced a marked increase insulin secretion and cAMP content.In 16.7 mmol/L glucose,after added EGTA or nifedipine,GLP-1(7-36)NH 2 could not induce insulin secretion with increasing cAMP content.Conclusion\ GLP-1(7-36)NH 2 stimulates of stimulating production of cAMP in a glucose concentration-dependent manner. Elevated cAMP in β-cells is the key in inducing insulin secretion.